E1 interface setup in NG-RAN

ABSTRACT

Systems and methods of setting up an E1 interface for a gNB are described, A transmitting entity of the gNB-CU-CP and gNB-CU-UP initiates the first TNL association between the gNB-CU-CP and gNB-CU-UP, and is also limited to initiating the E1 Setup procedure. The transmitting entity sends an E1 SETUP REQUEST message to set up the E1 interface. Afterwards, a message is received from the receiving entity. The transmitting entity determines that the setup of the E1 interface is successful if the message contains IEs of an E1 SETUP RESPONSE message. The types of IEs include a message type IE and a name of the transmitting entity.

This application is a continuation of U.S. patent application Ser. No.16/393,753, filed Apr. 24, 2019, which claims the benefit of priorityunder 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No.62/669,780, filed May 10, 2018, which are incorporated herein byreference in their entirety.

The claims in the instant application are different than those of theparent application and/or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication and/or any predecessor application in relation to theinstant application. Any such previous disclaimer and the citedreferences that it was made to avoid, may need to be revisited. Further,any disclaimer made in the instant application should not be read intoor against the parent application and/or other related applications.

TECHNICAL FIELD

Embodiments pertain to radio access networks (RANs). Some embodimentsrelate to cellular networks, including Third Generation PartnershipProject (3GPP) 5^(th) generation (5G) New Radio (NR) (or next generation(NG)) networks. Some embodiments relate to setup of the E1 interface.

BACKGROUND

The use of various types of systems has increased due to both anincrease in the types of devices user equipment (UEs) using networkresources as well as the amount of data and bandwidth being used byvarious applications, such as video streaming, operating on these UEs.To increase the ability of the network to contend with the explosion innetwork use and variation, the next generation of communication systemsis being created. With the advent of any new technology, theintroduction of a complex new communication system engenders a largenumber of issues to be addressed both in the system itself and incompatibility with previous systems and devices. Such issues arise, forexample, in establishing the E1 interface in 5G NodeBs (gNB), which isinefficient.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various aspects discussed in the present document.

FIG. 1 illustrates combined communication system in accordance with someembodiments.

FIG. 2 illustrates a block diagram of a communication device inaccordance with some embodiments.

FIG. 3 illustrates interconnections for gNBs in accordance with someembodiments.

FIGS. 4A and 4B show an E1 setup procedure in accordance with someembodiments.

FIGS. 5A and 5B show another E1 setup procedure in accordance with someembodiments.

FIGS. 6A and 6B show another E1 setup procedure in accordance with someembodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific aspects to enable those skilled in the art to practice them.Other aspects may incorporate structural, logical, electrical, process,and other changes. Portions and features of some aspects may be includedin, or substituted for, those of other aspects. Aspects set forth in theclaims encompass all available equivalents of those claims.

FIG. 1 illustrates a combined communication system in accordance withsome embodiments. The system 100 includes 3GPP LTE/4G and NG networkfunctions. A network function can be implemented as a discrete networkelement on a dedicated hardware, as a software instance running ondedicated hardware, or as a virtualized function instantiated on anappropriate platform, e.g., dedicated hardware or a cloudinfrastructure.

The evolved packet core (EPC) of the LTE/4G network contains protocoland reference points defined for each entity. These core network (CN)entities may include a mobility management entity (MME) 122, servinggateway (S-GW) 124, and paging gateway (P-GW) 126.

In the NG network, the control plane and the user plane may beseparated, which may permit independent scaling and distribution of theresources of each plane. The UE 102 may be connected to either an accessnetwork or random access network (RAN) 110 and/or may be connected tothe NG-RAN 130 (gNB) or an Access and Mobility Function (AMF) 142. TheRAN may be an eNB, a gNB or a general non-3GPP access point, such asthat for Wi-Fi. The NG core network may contain multiple networkfunctions besides the AMF 112. The network functions may include a UserPlane Function (UPF) 146, a Session Management Function (SMF) 144, aPolicy Control Function (PCF) 132, an Application Function (AF) 148, anAuthentication Server Function (AUSF) 152 and User Data Management (UDM)128. The various elements are connected by the NG reference points shownin FIG. 1 .

The AMF 142 may provide UE-based authentication, authorization, mobilitymanagement, etc. The AMF 142 may be independent of the accesstechnologies. The SMF 144 may be responsible for session management andallocation of IP addresses to the UE 102. The SMF 144 may also selectand control the UPF 146 for data transfer. The SMF 144 may be associatedwith a single session of the UE 102 or multiple sessions of the UE 102.This is to say that the UE 102 may have multiple 5G sessions. DifferentSMFs may be allocated to each session. The use of different SMFs maypermit each session to be individually managed. As a consequence, thefunctionalities of each session may be independent of each other. TheUPF 126 may be connected with a data network, with which the UE 102 maycommunicate, the UE 102 transmitting uplink data to or receivingdownlink data from the data network.

The AF 148 may provide information on the packet flow to the PCF 132responsible for policy control to support a desired QoS. The PCF 132 mayset mobility and session management policies for the UE 102. To thisend, the PCF 132 may use the packet flow information to determine theappropriate policies for proper operation of the AMF 142 and SMF 144.The AUSF 152 may store data for UE authentication. The UDM 128 maysimilarly store the UE subscription data.

The gNB 130 may be a standalone gNB or a non-standalone gNB, e.g.,operating in Dual Connectivity (DC) mode as a booster controlled by theeNB 110 through an X2 or Xn interface. At least some of functionality ofthe EPC and the NG CN may be shared (alternatively, separate componentsmay be used for each of the combined component shown). The eNB 110 maybe connected with an MME 122 of the EPC through an S1 interface and witha SGW 124 of the EPC 120 through an S1-U interface. The MME 122 may beconnected with an HSS 128 through an Sha interface while the UDM isconnected to the AMF 142 through the N8 interface. The SGW 124 mayconnected with the PGW 126 through an S5 interface (control plane PGW-Cthrough S5-C and user plane PGW-U through S5-U). The PGW 126 may serveas an IP anchor for data through the internet.

The NG CN, as above, may contain an AMF 142, SMF 144 and UPF 146, amongothers. The eNB 110 and gNB 130 may communicate data with the SGW 124 ofthe EPC 120 and the UPF 146 of the NG CN. The MME 122 and the AMF 142may be connected via the N26 interface to provide control informationthere between, if the N26 interface is supported by the EPC 120. In someembodiments, when the gNB 130 is a standalone gNB, the 5G CN and the EPC120 may be connected via the N26 interface.

FIG. 2 illustrates a block diagram of a communication device inaccordance with some embodiments. In some embodiments, the communicationdevice may be a UE, eNB, gNB or other equipment used in the networkenvironment. For example, the communication device 200 may be aspecialized computer, a personal or laptop computer (PC), a tablet PC, apersonal digital assistant (PDA), a mobile telephone, a smart phone, aweb appliance, a network router, switch or bridge, or any machinecapable of executing instructions (sequential or otherwise) that specifyactions to be taken by that machine. In some embodiments, thecommunication device 200 may be embedded within other, non-communicationbased devices such as vehicles and appliances.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules and componentsare tangible entities (e.g., hardware) capable of performing specifiedoperations and may be configured or arranged in a certain manner. In anexample, circuits may be arranged (e.g., internally or with respect toexternal entities such as other circuits) in a specified manner as amodule. In an example, the whole or part of one or more computer systems(e.g., a standalone, client or server computer system) or one or morehardware processors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a machine readable medium. In an example, thesoftware, when executed by the underlying hardware of the module, causesthe hardware to perform the specified operations.

Accordingly, the term “module” (and “component”) is understood toencompass a tangible entity, be that an entity that is physicallyconstructed, specifically configured (e.g., hardwired), or temporarily(e.g., transitorily) configured (e.g., programmed) to operate in aspecified manner or to perform part or all of any operation describedherein. Considering examples in which modules are temporarilyconfigured, each of the modules need not be instantiated at any onemoment in time. For example, where the modules comprise ageneral-purpose hardware processor configured using software, thegeneral-purpose hardware processor may be configured as respectivedifferent modules at different times. Software may accordingly configurea hardware processor, for example, to constitute a particular module atone instance of time and to constitute a different module at a differentinstance of time.

The communication device 200 may include a hardware processor 202 (e.g.,a central processing unit (CPU), a GPU, a hardware processor core, orany combination thereof), a main memory 204 and a static memory 206,some or all of which may communicate with each other via an interlink(e.g., bus) 208. The main memory 204 may contain any or all of removablestorage and non-removable storage, volatile memory or non-volatilememory. The communication device 200 may further include a display unit210 such as a video display, an alphanumeric input device 212 (e.g., akeyboard), and a user interface (UI) navigation device 214 (e.g., amouse). In an example, the display unit 210, input device 212 and UInavigation device 214 may be a touch screen display. The communicationdevice 200 may additionally include a storage device (e.g., drive unit)216, a signal generation device 218 (e.g., a speaker), a networkinterface device 220, and one or more sensors, such as a globalpositioning system (GPS) sensor, compass, accelerometer, or othersensor. The communication device 200 may further include an outputcontroller, such as a serial (e.g., universal serial bus (USB),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) connection to communicate or control one ormore peripheral devices (e.g., a printer, card reader, etc.).

The storage device 216 may include a non-transitory machine readablemedium 222 (hereinafter simply referred to as machine readable medium)on which is stored one or more sets of data structures or instructions224 (e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 224 may alsoreside, successfully or at least partially, within the main memory 204,within static memory 206, and/or within the hardware processor 202during execution thereof by the communication device 200. While themachine readable medium 222 is illustrated as a single medium, the term“machine readable medium” may include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) configured to store the one or more instructions 224.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe communication device 200 and that cause the communication device 200to perform any one or more of the techniques of the present disclosure,or that is capable of storing, encoding or carrying data structures usedby or associated with such instructions. Non-limiting machine readablemedium examples may include solid-state memories, and optical andmagnetic media. Specific examples of machine readable media may include:non-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks.

The instructions 224 may further be transmitted or received over acommunications network using a transmission medium 226 via the networkinterface device 220 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks. Communications over the networks may include one or moredifferent protocols, such as Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 family of standards known as Wi-Fi, IEEE 802.16family of standards known as WiMax, IEEE 802.15.4 family of standards, aLong Term Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, a NG/NR standards among others. In an example, the networkinterface device 220 may include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tothe transmission medium 226.

One advantage of the NR system is that the UE may be able to takeadvantage of a dual-connectivity (DC) framework, in which the UE may beconnected simultaneously with a master NodeB (MNB) and a secondary NodeB(SNB). The MNB and SNB may be eNBs, gNBs, or a combination thereof, forexample. In some embodiments, the MNB may use a single SNB for a bearerassociated with the UE. In some embodiments, the MNB may service the UE,so that all UL and DL data flow associated with the bearer is controlledby the MNB. For example, the MNB may transmit packets to the SNB fordelivery to the UE. The SNB may provide the MNB with information aboutpacket transmission or delivery to permit the MNB to control packet flowto the SNB to avoid overflow or underflow buffer issues associated withpacket delivery to the UE. The packet and control flow may betransmitted over an X2 interface when the MNB and SNB are eNBs over anXn interface when the MNB and SNB are gNBs (although a combination ofeNB and gNB may be used as well). FIG. 3 illustrates interconnectionsfor gNBs in accordance with some embodiments.

As shown in FIG. 3 , the gNBs 310 a, 310 b of the NG-RAN 310 may each beconnected with different AMFs 302 and UPFs 304 through an NG-Controlplane (NG-C or, as indicated in FIG. 1 , N2) interface and an NG-Userplane (NG-U or, as indicated in FIG. 1 , N3) interface, respectively. Insome embodiments, the gNBs 310 a, 310 b The gNBs 310 a, 310 b may beconnected with each other via dual Xn interfaces for control planesignaling (Xn-C) and user plane signaling (Xn-U). The control planefunctions of the Xn-C interface may include interface management anderror handling functionality, connected mode mobility management,support of RAN paging and dual connectivity functions, among others.Examples of the interface management and error handling functionalityinclude setup, reset, removal and configuration update of the Xninterface. Examples of connected mode mobility management includehandover procedures, sequence number status transfer and UE contextretrieval. Examples of dual connectivity functions include secondarynode addition, reconfiguration, modification, and release of thesecondary node. The user plane functions of the Xn-U interface mayinclude both data forwarding and flow control between the gNBs 310 a,310 b.

Each of the gNBs 310 a, 310 b may implement protocol entities in the3GPP protocol stack, in which the layers are considered to be ordered,from lowest to highest, in the order Physical (PHY), Medium AccessControl (MAC), Radio Link Control (RLC), Packet Data Convergence Control(PDCP), and Radio Resource Control (RRC)/Service Data AdaptationProtocol (SDAP) (for the control plane/user plane). The protocol layersin each gNB 310 a, 310 b may be distributed in different units—a CentralUnit (CU) 312, at least one Distributed Unit (DU) 314, and a RemoteRadio Head (RRH) 316. The CU 312 may provide functionalities such as thecontrol the transfer of user data, and effect mobility control, radioaccess network sharing, positioning, and session management, exceptthose functions allocated exclusively to the DU 314.

As shown in FIG. 3 , the higher protocol layers (PDCP and RRC for thecontrol plane/PDCP and SDAP for the user plane) may be implemented inthe CU 312, and the RLC and MAC layers may be implemented in the DU 314.The PHY layer may be split, with the higher PHY layer also implementedin the DU 314, while the lower PHY layer is implemented in the RemoteRadio Head 316. The CU 312, DU 314 and RRH 316 may be implemented bydifferent manufacturers, but may nevertheless be connected by theappropriate interfaces therebetween. The CU 312 may be connected withmultiple DUs 314.

The interfaces within the gNB include the E1 and front-haul (F) F1interface. As shown, a F2 interface may also be present, but thestandards for this interface has not been developed yet. The E1interface may be between a CU control plane (gNB-CU-CP) and the CU userplane (gNB-CU-UP) and thus may support the exchange of signalinginformation between the control plane and the user plane through E1APservice. The E1 interface may separate Radio Network Layer and TransportNetwork Layer and enable exchange of UE associated information andnon-UE associated information. The E1AP services may be nonUE-associated services that are related to the entire E1 interfaceinstance between the gNB-CU-CP and gNB-CU-UP using a non UE-associatedsignaling connection and UE-associated services that are related to asingle UE and are associated with a UE-associated signaling connectionthat is maintained for the UE. The E1AP services may include an E1interface management function, an E1 bearer context management functionand allocation of tunnel endpoint identifiers (TEIDs).

The F1 interface may be disposed between the CU 312 and the DU 314. TheCU 312 may control the operation of the DU 314 over the F1 interface. Asthe signaling in the gNB is split into control plane and user planesignaling, the F1 interface may be split into the F1-C interface forcontrol plane signaling and the F1-U interface for user plane signaling,which support control plane and user plane separation. The F1 interface,as above may separate the Radio Network and Transport Network Layers andenable exchange of UE associated information and non-UE associatedinformation.

The F2 interface may be between the lower and upper parts of the NR PHYlayer. The F2 interface may also be separated into F2-C and F2-Uinterfaces based on control plane and user plane functionalities.

Before the various interfaces may be used, the gNB may engage in a setupprocedure for each interface. For example, the GNB-CU-UP E1 Setupprocedure may exchange application level data used for the gNB-CU-UP andthe gNB-CU-CP to correctly interoperate on the E1 interface. TheGNB-CU-CP E1 setup procedure similarly may exchange application leveldata used for the gNB-CU-CP and the gNB-CU-UP to correctly interoperateon the E1 interface. If the gNB-CU-UP or gNB-CU-CP initiates the firstTransport Network Layer (TNL) association, the gNB-CU-UP or gNB-CU-CPmay also initiate the GNB-CU-UP E1 Setup procedure or the GNB-CU-CP E1Setup procedure, respectively. The GNB-CU-UP E1 and GNB-CU-CP E1 Setupprocedures may use non-UE associated signaling, erase existingapplication level configuration data in the nodes and replaces theconfiguration by the configuration received, re-initialize the E1APUE-related contexts and erase related signaling connections in thenodes.

Thus, both the gNB-CU-CP and gNB-CU-UP may send an E1 SETUP REQUESTafter TNL association has become operational. Contention may occur ifthe gNB-CU-CP and gNB-CU-UP send E1 SETUP REQUEST simultaneously. Forexample, from the gNB-CU-CP's perspective, a few milliseconds aftersending a GNB-CU-CP E1 SETUP REQUEST, the gNB-CU-CP may receive aGNB-CU-UP E1 SETUP REQUEST, rather than the expected GNB-CU-CP E1 SETUPRESPONSE (or GNB-CU-CP E1 SETUP FAILURE). Similarly, from thegNB-CU-UP's perspective, a few milliseconds after sending a GNB-CU-UP E1SETUP REQUEST, the gNB-CU-UP may receive a GNB-CU-CP E1 SETUP REQUEST,rather than the expected GNB-CU-UP E1 SETUP RESPONSE (or GNB-CU-UP E1SETUP FAILURE). The four-message procedure is, however, inefficient.

To alleviate this, FIGS. 4A and 4B show an E1 setup procedure inaccordance with some embodiments. FIGS. 4A and 4B show a successful E1setup procedure in which the gNB-CU-CP and the gNB-CU-UP send aGNB-CU-CP E1 SETUP REQUEST and a GNB-CU-UP E1 SETUP REQUESTsimultaneously. However, the information elements (IEs) in the GNB-CU-CPE1 SETUP REQUEST and GNB-CU-UP E1 SETUP REQUEST are designed so that theIEs or types of IEs are the same as those in the GNB-CU-UP E1 SETUPRESPONSE and GNB-CU-CP E1 SETUP RESPONSE. Thus, the gNB-CU-CP may takethe GNB-CU-UP E1 SETUP REQUEST as the GNB-CU-CP E1 SETUP RESPONSE, andthe gNB-CU-UP may take the GNB-CU-CP E1 SETUP REQUEST as the GNB-CU-UPE1 REPONSE. FIGS. 4A and 4B show simultaneous transmission of theGNB-CU-CP E1 SETUP REQUEST and the GNB-CU-UP E1 SETUP REQUEST in whicheither the GNB-CU-CP E1 SETUP REQUEST or the GNB-CU-UP E1 SETUP REQUESTis transmitted slightly before the other.

An example of the IEs in the GNB-CU-CP E1 SETUP REQUEST and theGNB-CU-UP E1 SETUP RESPONSE can be as shown in table 1.

TABLE 1 Assigned IE/Group Name Presence Criticality Message Type Mreject gNB-CU-CP ID M reject gNB-CU-CP Name O ignore

The Message Type IE may uniquely identify the message being sent. ThegNB-CU-CP Name IE may be used as a human readable name of the gNB-CU-CP.An example of the IEs in the GNB-CU-UP E1 SETUP REQUEST and theGNB-CU-CP E1 SETUP RESPONSE can be as shown in table 2.

TABLE 2 Semantics Assigned IE/Group Name Presence descriptionCriticality Message Type M reject gNB-CU-UP ID M reject gNB-CU-UP Name Oignore Supported 5QI M reject Security information NR CGI M rejectBroadcast PLMNs Broadcast Reject PLMNs >PLMN Identity M — >Slice SupportList O Supported S- — NSSAIs

In the above embodiment, as in the other embodiments described herein,the request/response used to set up the E1 interface and the informationcontained therein (IEs) are stored in a memory associated with the gNB.

Another embodiment to reduce the inefficiency above is shown in FIGS. 5Aand 5B, which show another E1 setup procedure in accordance with someembodiments. In particular, FIGS. 5A and 5B show a successful E1 setupprocedure in which the gNB-CU-CP ignores the GNB-CU-UP E1 SETUP REQUESTin case of contention. Instead, after transmission of the GNB-CU-CP E1SETUP REQUEST, the gNB-CU-CP may wait until a GNB-CU-CP E1 SETUPRESPONSE or FAILURE is received from the gNB-CU-UP. In this case, thegNB-CU-UP may respond with a GNB-CU-CP E1 SETUP RESPONSE even if thegNB-CU-UP has sent a GNB-CU-UP E1 SETUP REQUEST before reception of theGNB-CU-CP E1 SETUP REQUEST when the requests are simultaneouslytransmitted. FIGS. 5A and 5B show simultaneous transmission of theGNB-CU-CP E1 SETUP REQUEST and the GNB-CU-UP E1 SETUP REQUEST in whicheither the GNB-CU-CP E1 SETUP REQUEST or the GNB-CU-UP E1 SETUP REQUESTis transmitted slightly before the other.

Another embodiment to reduce the inefficiency above is shown in FIGS. 6Aand 6B, which show another E1 setup procedure in accordance with someembodiments. In the embodiment shown in FIGS. 6A and 6B, the gNB-CU-UPignores the GNB-CU-CP E1 SETUP REQUEST in case of contention. Instead,the gNB-CU-UP may wait until a GNB-CU-UP E1 SETUP RESPONSE or FAILURE isreceived from the gNB-CU-CP. In this case, the gNB-CU-CP may respondwith a GNB-CU-UP E1 SETUP RESPONSE even if the gNB-CU-CP has sent aGNB-CU-CP E1 SETUP REQUEST before reception of the GNB-CU-UP E1 SETUPREQUEST when the requests are simultaneously transmitted. FIGS. 6A and6B show simultaneous transmission of the GNB-CU-CP E1 SETUP REQUEST andthe GNB-CU-UP E1 SETUP REQUEST in which either the GNB-CU-CP E1 SETUPREQUEST or the GNB-CU-UP E1 SETUP REQUEST is transmitted slightly beforethe other.

In another embodiment, E1 SETUP REQUEST and E1 SETUP RESPONSE aredesigned as in table 3, where only message type and ID is included.

TABLE 3 Assigned IE/Group Name Presence Criticality Message Type Mreject

In this case, after receiving the E1 SETUP RESPONSE, an E1 CONFIGURATIONUPDATE is then sent to provide the information of the gNB-CU-CP orgNB-CU-UP.

In another embodiment, after TNL association has become operational, thegNB-CU-UP may start a gNB-CU-UP timer after a determination by thegNB-CU-UP to send a GNB-CU-UP E1 SETUP REQUEST. The GNB-CU-UP E1 SETUPREQUEST can be sent by the gNB-CU-UP if a GNB-CU-CP E1 SETUP REQUEST hasnot been received before expiration of the gNB-CU-UP timer. Similarly,in another embodiment, after TNL association has become operational, thegNB-CU-CP may start a gNB-CU-CP timer after a determination by thegNB-CU-CP to send a GNB-CU-CP E1 SETUP REQUEST. The GNB-CU-CP E1 SETUPREQUEST can be sent if GNB-CU-UP E1 SETUP REQUEST has not been receivedbefore expiration of the gNB-CU-CP timer. In some embodiments, thegNB-CU-UP timer and the gNB-CU-CP timer may be able to be independentlyset. The gNB-CU-UP timer and the gNB-CU-CP timer may be symmetric (i.e.,be the same time period).

In yet another embodiment, transmission of the E1 SETUP REQUEST may belimited to whichever entity of the gNB-CU-CP and the gNB-CU-UP initiatesthe Stream Control Transmission Protocol (SCTP) connection procedure(i.e., the first TNL association). The E1 protocol stack may include anapplication layer signaling protocol (referred to as E1 ApplicationProtocol (E1-AP)) and a transport network layer that is built on SCTP.SCTP is a protocol for transmitting multiple streams of data at the sametime between two end points that have established a connection in anetwork. Like TCP, SCTP manages reliable transport (ensuring thecomplete arrival of PDUs that are sent over the network) over IP. SCTPmay thus be on top of an IP layer, and may provide the guaranteeddelivery of application layer messages. Unlike TCP, SCTP may ensure thecomplete concurrent transmission of several streams of data betweenconnected end points. The multi-streaming allows data to be delivered inmultiple, independent streams, so that if there is data loss in onestream, delivery will not be affected for the other streams.

In particular, each SCTP endpoint identifies the SCTP association with atag. During an SCTP association setup, the SCTP endpoints exchange theirown tags for receiving packets. During the exchange of packets betweenthe SCTP endpoints, both the source address and the destination addresscan change in the association life cycle. SCTP also supportsmultihoming, which means that a connected end point can have up to 8alternate IP addresses to route around network failure or changingconditions. Data using SCTP is delivered in chunks within an independentstream, and, as above, the path is selected and monitored to select aprimary data transmission path and test the connectivity of thetransmission path. Validation and acknowledgment mechanisms providenotification of duplicated or missing data chunks, and error detectionis suitable for jumbo Ethernet frames.

The SCTP packet structure includes a common header section of the first12 bytes of the packet and that includes the source and destination portnumber, a verification tag checksum, and a data chunk section. The datachunk section contains, for each data chunk: the type (1 byte), flags (8bits), length (2 bytes) and value of the chunk. The destination portnumber may be used to route the packet to the appropriate destination orapplication. The verification tag is a 32-bit random value createdduring initialization and that distinguishes stale packets from aprevious connection. The checksum uses cyclic redundancy check (CRC32)algorithm to detect errors introduced during data transmission. Thechunk type identifies the contents of the chunk value field. The chunkflags depend on the chunk type. A default value of zero indicates thatno application identifier is specified by the upper layer for the data.

Thus, in some embodiments if the gNB-CU-UP, in response to transmissionof the GNB-CU-UP E1 SETUP REQUEST, does not receive the GNB-CU-UP E1SETUP RESPONSE message or GNB-CU-UP E1 SETUP FAILURE message, thegNB-CU-UP may reinitiate the gNB-CU-UP E1 Setup procedure towards thesame gNB-CU-CP. The content of the new GNB-CU-UP E1 SETUP REQUESTmessage may be identical to the content of the previously unacknowledgedGNB-CU-UP E1 SETUP REQUEST message. Similarly, if the gNB-CU-CP, inresponse to transmission of the GNB-CU-CP E1 SETUP REQUEST, does notreceive the GNB-CU-CP E1 SETUP RESPONSE message or GNB-CU-CP E1 SETUPFAILURE message, the gNB-CU-CP may reinitiate the gNB-CU-CP E1 Setupprocedure towards the same gNB-CU-UP. The content of the new GNB-CU-CPE1 SETUP REQUEST message may be identical to the content of thepreviously unacknowledged GNB-CU-CP E1 SETUP REQUEST message.

Although an aspect has been described with reference to specific exampleaspects, it will be evident that various modifications and changes maybe made to these aspects without departing from the broader scope of thepresent disclosure. Accordingly, the specification and drawings are tobe regarded in an illustrative rather than a restrictive sense. Theaccompanying drawings that form a part hereof show, by way ofillustration, and not of limitation, specific aspects in which thesubject matter may be practiced. The aspects illustrated are describedin sufficient detail to enable those skilled in the art to practice theteachings disclosed herein. Other aspects may be utilized and derivedtherefrom, such that structural and logical substitutions and changesmay be made without departing from the scope of this disclosure. ThisDetailed Description, therefore, is not to be taken in a limiting sense,and the scope of various aspects is defined only by the appended claims,along with the full range of equivalents to which such claims areentitled.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single aspect for the purpose of streamlining the disclosure. Thismethod of disclosure is not to be interpreted as reflecting an intentionthat the claimed aspects require more features than are expresslyrecited in each claim. Rather, as the following claims reflect,inventive subject matter lies in less than all features of a singledisclosed aspect. Thus, the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate aspect.

What is claimed is:
 1. A computer-readable non-transitory storage mediumthat stores instructions for execution by one or more processors of anext generation NodeB (gNB), the one or more processors to configure thegNB to, when the instructions are executed: initiate, by one of acentral unit control plane (gNB-CU-CP) and a central unit user plane(gNB-CU-UP), a first stream control transmission protocol (SCTP)connection between the gNB-CU-CP and gNB-CU-UP; and subsequentlyinitiate an E1 Setup procedure to set up an E1 interface between thegNB-CU-CP and the gNB-CU-UP, wherein initiation of the E1 Setupprocedure is performed by the gNB-CU-CP when the gNB-CU-CP initiated thefirst SCTP connection, and wherein initiation of the E1 Setup procedureis performed by the gNB-CU-UP when the gNB-CU-UP initiated the firstSCTP connection.
 2. The medium of claim 1, wherein: when initiation ofthe E1 Setup procedure is performed by the gNB-CU-UP, and the E1 Setupprocedure is a gNB-CU-UP E1 Setup procedure.
 3. The medium of claim 1,wherein: when initiation of the E1 Setup procedure is performed by thegNB-CU-CP, and the E1 Setup procedure is a gNB-CU-CP E1 Setup procedure.4. The medium of claim 1, wherein the one or more processors furtherconfigure the gNB to, when the instructions are executed: initiate theE1 Setup procedure by transmission of an E1 SETUP REQUEST message, anddetermine that setup of the E1 interface is successful in response toreception of a message that contains information elements (IEs) of an E1SETUP RESPONSE message in response to transmission of the E1 SETUPREQUEST message, wherein the E1 SETUP REQUEST message and E1 SETUPRESPONSE message sent by a same entity of the gNB-CU-CP and gNB-CU-UPconsist of identical types of the IEs.
 5. The medium of claim 4, whereinwhen initiation of the E1 Setup procedure is performed by the gNB-CU-CP:the E1 SETUP REQUEST message is a GNB-CU-CP E1 SETUP REQUEST message,and the E1 SETUP RESPONSE message is a GNB-CU-CP E1 SETUP RESPONSEmessage.
 6. The medium of claim 5, wherein: the GNB-CU-CP E1 SETUPREQUEST message and the GNB-CU-CP E1 SETUP RESPONSE message comprise amessage type IE that identifies the message being sent and a gNB-CU-CPName IE that indicates a name of the gNB-CU-CP.
 7. The medium of claim4, wherein when initiation of the E1 Setup procedure is performed by thegNB-CU-UP: the E1 SETUP REQUEST message is a GNB-CU-UP E1 SETUP REQUESTmessage, and the E1 SETUP RESPONSE message is a GNB-CU-UP E1 SETUPRESPONSE message.
 8. The medium of claim 7, wherein: the GNB-CU-UP E1SETUP REQUEST message and the GNB-CU-UP E1 SETUP RESPONSE messagecomprise a message type IE that identifies the message being sent, agNB-CU-UP identity (ID) IE that identifies the gNB-CU-UP, and agNB-CU-CP Name IE that indicates a name of the gNB-CU-CP.
 9. The mediumof claim 4, wherein: the E1 SETUP REQUEST message and E1 SETUP RESPONSEmessage from the gNB-CU-CP and gNB-CU-UP comprise setup IEs of a sametype, including a message type IE and a name of one of the gNB-CU-CP andgNB-CU-UP that has respectively transmitted the E1 SETUP REQUEST messageand E1 SETUP RESPONSE message.
 10. The medium of claim 4, wherein theone or more processors further configure the gNB to, when theinstructions are executed: if the E1 SETUP RESPONSE message in responseto transmission of the E1 SETUP REQUEST message has not been received,wait a predetermined amount of time after transmission of the E1 SETUPREQUEST message before re-transmission of the E1 SETUP REQUEST message.11. An apparatus of a next generation NodeB (gNB), the apparatuscomprising: processing circuitry; and memory, wherein the gNB isconfigured with logical nodes including a gNB central unit (gNB-CU) anda gNB distributed unit (gNB-DU), the gNB-CU comprising a gNB-CU controlplane (gNB-CU-CP) for control-plane functionality and a gNB-CU userplane (gNB-CU-UP) for user-plane functionality, the gNB-CU-CP configuredto communicate with the gNB-CU-UP over an E1 interface, the gNB-CU-UPconfigured to communicate user plane messages with the gNB-DU over an F1user-plane interface (F1-U), the gNB-CU-CP is configured to communicatecontrol plane messages with the gNB-DU over an F1 control planeinterface (F1-C), the processing circuitry configured to: initiate, byone of the gNB-CU-CP and gNB-CU-UP, a first stream control transmissionprotocol (SCTP) connection between the gNB-CU-CP and gNB-CU-UP; andsubsequently initiate an E1 Setup procedure to set up the E1 interfacebetween the gNB-CU-CP and the gNB-CU-UP, wherein initiation of the E1Setup procedure is performed by the gNB-CU-CP when the gNB-CU-CPinitiated the first SCTP connection, and wherein initiation of the E1Setup procedure is performed by the gNB-CU-UP when the gNB-CU-UPinitiated the first SCTP connection; and a memory configured to storeinformation of the E1 Setup procedure.
 12. The apparatus of claim 11,wherein: when initiation of the E1 Setup procedure is performed by thegNB-CU-UP, the E1 Setup procedure is a gNB-CU-UP E1 Setup procedure. 13.The apparatus of claim 11, wherein: when initiation of the E1 Setupprocedure is performed by the gNB-CU-CP, the E1 Setup procedure is agNB-CU-CP E1 Setup procedure.
 14. The apparatus of claim 11, wherein theone or more processors further configure the gNB to, when theinstructions are executed: initiate the E1 Setup procedure bytransmission of an E1 SETUP REQUEST message, and determine that setup ofthe E1 interface is successful in response to reception of a messagethat contains information elements (IEs) of an E1 SETUP RESPONSE messagein response to transmission of the E1 SETUP REQUEST message, wherein theE1 SETUP REQUEST message and E1 SETUP RESPONSE message sent by a sameentity of the gNB-CU-CP and gNB-CU-UP consist of identical types of theIEs.
 15. The apparatus of claim 14, wherein when initiation of the E1Setup procedure is performed by the gNB-CU-CP: the E1 SETUP REQUESTmessage is a GNB-CU-CP E1 SETUP REQUEST message, the E1 SETUP RESPONSEmessage is a GNB-CU-CP E1 SETUP RESPONSE message, and the GNB-CU-CP E1SETUP REQUEST message and the GNB-CU-CP E1 SETUP RESPONSE messagecomprise a message type IE that identifies the message being sent and agNB-CU-CP Name IE that indicates a name of the gNB-CU-CP.
 16. Theapparatus of claim 14, wherein when initiation of the E1 Setup procedureis performed by the gNB-CU-uP: the E1 SETUP REQUEST message is aGNB-CU-UP E1 SETUP REQUEST message, the E1 SETUP RESPONSE message is aGNB-CU-UP E1 SETUP RESPONSE message, and the GNB-CU-UP E1 SETUP REQUESTmessage and the GNB-CU-UP E1 SETUP RESPONSE message comprise a messagetype IE that identifies the message being sent, a gNB-CU-UP identity(ID) IE that identifies the gNB-CU-UP, and a gNB-CU-CP Name IE thatindicates a name of the gNB-CU-CP.
 17. The apparatus of claim 14,wherein: the E1 SETUP REQUEST message and E1 SETUP RESPONSE message fromthe gNB-CU-CP and gNB-CU-UP comprise setup IEs of a same type, includinga message type IE and a name of one of the gNB-CU-CP and gNB-CU-UP thathas respectively transmitted the E1 SETUP REQUEST message and E1 SETUPRESPONSE message.
 18. The apparatus of claim 14, wherein the processingcircuitry is further configured to: if the E1 SETUP RESPONSE message inresponse to transmission of the E1 SETUP REQUEST message has not beenreceived, wait a predetermined amount of time after transmission of theE1 SETUP REQUEST message before re-transmission of the E1 SETUP REQUESTmessage.
 19. An apparatus of a central unit control plane of a nextgeneration NodeB (gNB-CU-CP), the apparatus comprising: processingcircuitry configured to: initiate a first stream control transmissionprotocol (SCTP) connection between the gNB-CU-CP and a central unit userplane (gNB-CU-UP); and subsequently initiate an E1 Setup procedure toset up an E1 interface between the gNB-CU-CP and gNB-CU-UP, whereinestablishment of the E1 interface is limited to the gNB-CU-CP andcomprises: transmission of a gNB-CU-CP E1 SETUP REQUEST message, anddetermination that setup of the E1 interface is successful in responseto reception of a message that contains information elements (IEs) of agNB-CU-CP E1 SETUP RESPONSE message in response to transmission of thegNB-CU-CP E1 SETUP REQUEST message; and a memory configured to store theIEs of the gNB-CU-CP E1 SETUP REQUEST message.
 20. The apparatus ofclaim 19, wherein: the gNB-CU-CP E1 SETUP RESPONSE message and aGNB-CU-CP E1 SETUP REQUEST message consist of identical types of theIEs.